1. Field of the Invention
The present invention concerns an improvement to a liquid waste processing apparatus for separating an recovering floating sludge such as paint dust that is contained in liquid wastes discharged from a coating booth or the like.
2. Description of the Prior Art
Since liquid wastes discharged from a coating booth contain chemicals such as so-called killer agents used for separating paints from water, a great amount of floating sludge such as paint dust is caused to float on the liquid surface of a liquid waste processing pool into which the liquid wastes are discharged.
For separating and recovering the floating sludges from the liquid wastes, a movable float has been used, which is caused to float on the liquid surface of a liquid waste processing pool, so that the floating sludges on the liquid wastes are sucked up by a vacuum suction pipe attached to the float and sent to a filtration device for recovery (refer, for example, to Japanese Patent Unexamined Publication No. Sho 63-162093 and Japanese Utility Model Unexamined Publication No. Sho 62-56173).
However, it has been difficult for the float to run after the floating sludges scattered over the entire area of the liquid surface in the liquid waste processing pool and completely suck them up using the vacuum suction pipe in addition, the mechanism used for moving the float and the control therefor are very complicated increasing the installation cost, as well as the filtration device often causes failure due to the viscosity of the floating sludges, to remarkably increase the installation cost and the operation cost.
In view of the above, the present applicant has previously proposed a liquid waste processing apparatus capable of automatically collecting floating sludges that are contained in the liquid wastes discharged from a coating booth to a localized portion and recoverying them by a simple mechanism (Japanese Utility Model Application No. Sho 63-40338).
In this proposed apparatus, a liquid waste processing vessel has an inlet disposed on one side wall into which liquid wastes fall from above and from which the liquid wastes leave with bubbles entrained therein, an exit disposed on the other opposite side wall, and an inclined plate disposed above the exit against which the flow of the liquid wastes is abutted and then turned toward the exit again.
In this apparatus, the floating sludges contained in the liquid wastes are adsorbed to the bubbles involved in the flow of the wastes and transported along with a surface stream from the inlet to the exit. When the flow of the liquid wastes reaches the inclined plate, it abuts against the plate and turns its direction toward the inlet while leaving the floating sludges as they are at a localized area above the inclined plate Then, the sludges completely separated from the liquid wastes are discharged out of the processing vessel and treated in a filtration tank. Meanwhile, the liquid wastes removed with the sludges flow along the downwardly sloped inclined plate and then are discharged from the exit for recyclical use.
Thus, the floating sludges can be separated from the liquid wastes easily in a simple structure with no substantial moving components.
However, even in this proposed apparatus, a portion of the floating sludges may sometime stagnate on the liquid surface in the inlet or along the lower surface of the inclined plate. Further, precipitating sludges contained in the liquid wastes ma be deposited at the bottom of the liquid waste processing vessel, to necessitate frequent cleaning operation for the vessel.